U.S. Pat. Nos. 4,193,654, 4,210,376, and 4,221,458 show a known type of electrical connector assembly which is coming into widespread use in the communications industry and on computer and computer related equipment. The receptacles shown in the above identified U.S. patents are dimensioned to receive connector plugs of the general type shown in U.S. Pat. No. 3,860,316.
The receptacles and plugs referred to above usually have no more than eight terminals therein and it is usually not considered necessary to provide keying systems to key a particular plug to a particular receptacle. However, there is a need for connector assemblies of the general type described above having greatly increased numbers of contact terminals therein and there is a need for a family or series of connectors having varying numbers of terminals therein. These requirements are particularly felt by manufacturers of computers and computer-related equipment.
Where connector assemblies of the type under consideration are manufactured in a range of sizes, as regards the number of terminals in the assembly, it is possible to insert a plug part of the assembly having a lesser number of contact terminals into a receptacle having a greater number of contact terminals because of the fact that the plug and receptacle of two assemblies of different sizes differ only in the width of the plug and the width of the plug-receiving opening in the receptacle. It can readily be appreciated that as a number of connector assemblies of different sizes are mounted adjacent to each other, a plug might be mis-mated with a receptacle having a greater number of contact terminals than the plug; in other words, the plug can be simply inserted into the center portion of the plug-receiving opening of the receptacle. Obviously, the connector system for the equipment must preclude this possibility to avoid the potential for serious damage which might result from such mis-mating. In accordance with one embodiment thereof, the invention is directed to the achievement of a primary keying system for a series or family of electrical connector assemblies, the primary keying system functioning to prevent insertion of a relatively smaller plug into a larger receptacle than the size of the receptacle for which the plug is intended.
In addition to the need for a primary keying system, a conventional keying system is also required for connector assemblies of the type under consideration. If two connector assemblies of the same size (having the same number of terminals therein) are used in close proximity, it is possible to mis-mate the plugs and receptacles and the primary keying system discussed above would not preclude such mis-mating. A secondary keying system is thus needed specifically to keying a specific plug to a specific receptacle. The invention in accordance with a further aspect is directed to the achievement of an improved specific keying system and particularly to a specific keying system in combination with a primary keying system.
A preferred embodiment of the invention comprises a series of electrical connector assemblies, each assembly comprising a plug and a receptacle, each plug and each receptacle comprising a molded insulating housing having a mating end and a rearward end and having oppositely facing external housing sidewalls and oppositely facing external housing endwalls extending from the mating end to the rearward end. Each of the receptacles has a trough-like plug-receiving opening extending into its mating end, the plug-receiving opening in each receptacle having opposed plug opening sidewalls which are proximate to the external housing sidewalls and opposed plug opening endwalls which are proximate to the external housing endwalls. The plug of each connector assembly has a forward portion which extends from its mating end partially towards its rearward end and which is dimensioned to be received in the plug-receiving opening of the receptacle of the same assembly. A plurality of plug contacts are provided in the plug of each assembly and a like plurality of receptacle contacts in the receptacle of the same assembly. The receptacle contacts are within the plug receiving opening and are arranged in a row which extends between the plug opening endwalls. The plug contacts of each plug are proximate to the mating end of the plug and are arranged in a row which extends between the plug housing endwalls. The plug-receiving openings of the receptacles of the series are of increasing width, as measured between the plug opening endwalls, with increasing numbers of receptacle contacts in the receptacles, the plugs of the series similarly being of increasing width, as measured between the plug housing endwalls, with increasing numbers of plug contacts in the plugs. The height of the plug openings, as measured between the plug opening sidewalls, is uniform for all receptacles in the series. The series of electrical connectors is characterized in that a primary keying system is provided on the connector assemblies of the series, the primary keying system comprising, on each assembly of the series, at least one primary key on the receptacle of each assembly and at least one primary keyway in the plug of the same assembly, each primary key of the receptacle being aligned with a corresponding primary keyway of the plug of the same assembly.
The primary keys and primary keyways of the connector assemblies of the series having greater numbers of contacts are selectively located, relative to the locations of the primary keys and primary keyways of assemblies having lesser numbers of contacts, in a manner which prevents insertion of a plug having a lesser number of contacts into a receptacle having a greater number of contacts.
In accordance with a further embodiment, a secondary keying system is provided on the connector assemblies of the series for keying specifically a specific plug of the series to a specific receptacle. In accordance with a further embodiment, the secondary keys in the receptacles and secondary keyways in the plugs are dimensioned to preclude entry of a primary key therein into a secondary keyway.
A further embodiment comprises an electrical connector assembly of the type comprising a molded plug and a molded receptacle, the plug and receptacle being as described above. The assembly has a primary keying system comprising at least one primary key on the receptacle and at least one primary keyway in the plug. Each primary key of the receptacle is aligned with a corresponding primary keyway of the plug of the assembly. The primary keying system functions to permit insertion of the plug into the plug-receiving opening of the receptacle and to preclude insertion of a second plug, having a width as measured between its external housing endwalls which is less than the corresponding dimension of the plug, into the receptacle of the assembly.
In accordance with a further embodiment, a secondary keying system is provided in addition to the primary keying system, the secondary keying system functioning to prevent mis-mating of the plug and the receptacle with a substantially identical receptacle and a substantially identical plug respectively, which have the same primary keying system as the plug and receptacle.